1 JASPERSE CHEM 350 TEST 1 VERSION 4 Organic Chemistry I - Jasperse Intro and Review Structure and Properties of Organic Molecules Structure, Nomenclature, and Conformation/Stereochemistry of Alkanes 1. Order the following according to increasing electronegativity, 1 being highest, 4 lowest. (2pts) N F O C 2. Write Lewis structures and assign any non-zero formal charges. (3pts each) a. [CH 3 OH 2 ] + b. CH 3 CO 2 CH 2 ONa c. CH 3 CHCHCONH 2 3. For each of the following, a) draw its resonance structure, and for each pair b) circle the structure that would make the greater contribution to the resonance hybrid. (2 pts each) O O+ H b. a. 4. Draw line-angle structures for 7 of the 9 structural isomers of C 7 H 16 . (5 pts) T T T 2 Factors: 1. More bonds (priority) 2. Electronegativity (if bonds are equal) Alkane Acyclic: C n H 2n+2 Alkane Cyclic: C n H 2n Beware of drawing same thing twice! 1. Want normal bonding for all: in absence of metal ions or overall charge 2. C=O (or C=C in other cases) may help 3. If you have any formal charges, they must sum to net charge of molecule (zero, in this case) 4. Organization must match condensed formula sequence
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JASPERSE CHEM 350 TEST 1 VERSION 4 Organic Chemistry I - Jasperse Intro and Review Structure and Properties of Organic Molecules Structure, Nomenclature, and Conformation/Stereochemistry of Alkanes 1. Order the following according to increasing electronegativity, 1 being highest, 4 lowest. (2pts)
N F O C 2. Write Lewis structures and assign any non-zero formal charges. (3pts each)
a. [CH3OH2]+ b. CH3CO2CH2ONa c. CH3CHCHCONH2
3. For each of the following, a) draw its resonance structure, and for each pair b) circle the structure that would make the greater contribution to the resonance hybrid. (2 pts each)
O
O+Hb.
a.
4. Draw line-angle structures for 7 of the 9 structural isomers of C7H16. (5 pts)
T
T
T
2 Factors:1. More bonds (priority)2. Electronegativity(if bonds are equal)
Alkane Acyclic: CnH2n+2Alkane Cyclic: CnH2n
Beware of drawing samething twice!
1. Want normal bonding for all: in absence of metal ions or overall charge2. C=O (or C=C in other cases) may help3. If you have any formal charges, they must sum to net charge of molecule (zero, in this case)4. Organization must match condensed formula sequence
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5. For the following pairs of structures, identify them as either: Resonance Structures, Structural Isomers, Stereoisomers, or Same. (2 pts each)
OH O
H3CH H
CH3 H3CH CH3
H
(CH3)2CHCH2CH3CH3CH2CH2CH2CH3
a.
b.
c.
d.
e.
6. Rank the acidity of the following molecules, 1 being most acidic, 4 being least acidic. (3 pts)
CH3NH2 CH3OH HCO2H CH3CH3
7.
O O+ CH3+ CH4
a) Put a box around the weakest base in the above reaction. (1pt) b) Put a circle around the weakest acid in the above reaction. (1pt) c) Draw an arrow to show whether at equilibrium the reaction will go left-to-right or right-to-left. (2pt)
T
T
T
3 Acidity Factors:1. charge (not relevant here)2. Eneg3. Resonance
1. Resonance: No atoms can move!2. Stereo: same condensed formula3. Structural: different condensed formula
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8. Draw the line-angle structure for the following condensed structural formula: (CH3CH2)2CO (3pt)
9. H2N
98
7654
32
1 a. For the above structure, what is the hybridization, electron-pair geometry, and approximate bond angles (109, 120, or 180) about: (6pt) N-1 C-3 C-5 C-8 b. Rank the length of the following bonds, 1 being shortest, 3 being longest. (2pt) C2-C3 C4-C5 C8-C9
10. For each of the pairs listed, circle the one with the higher boiling point. (4pt)
O OH
Oc.
b.
a.
11. Draw a 3-dimensional picture for all of the atoms (hydrogens included) in the molecule
CH3CHCHCOCH2CH2NHCH3. Your picture should use the hash-wedge convention to illustrate atoms that are not in the plane of the paper, and should reflect approximate bond angles. (5pt)
T
T
T
2 factors:1. H-bonding (raises bp + solubility)2. London force (# of carbons)-more C's raises bp but reduces water solubility
Note: N-H hydrogen is NOT in the plane. But it could be drawn hashed or wedged, either is fifine.
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12. Draw a 3-D picture of CH2O showing the π bond as well as the four atoms. (3pt) 13. For the following set, rank the solubility in water, from 1 (most soluble) to 4 (least soluble).
(3pt)
OH OHO
14. Identify the functional groups in the following molecules. (8pt)
OO
HO N OHO
H
a.
b.
15. Give the IUPAC name for the following compounds. (6pt)
a.
HCH3CH3Hb.
T
T
T
1. Longest chain2. Alphabetize substituents3. Number from end near substituent
1. cis/trans for di-subbed rings2. Alphabetize substituents3. Numbering 4. Know isopropyl and t-butyl
p-orbitals used to make the pi-bond are perpendicular to the plane of the atoms. So if we draw the pi-bond in the plane, the attached H's must be out of plane.
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16. Draw the Newman projections for the best and worst conformations of butane, and give the names for these conformations. Briefly explain what “strain factors” make the worst conformation worse than the best conformation. (6pt)
17. a.) Draw both chair conformations of cis-1-methyl-2-isopropylcyclohexane. Draw the
substituents and H-atoms attached to carbons 1 and 2. (You don't need to show the H's on the other carbons). (4pt) b.) Circle the more stable conformation. (1pt)
18. Draw the best chair conformation for 1,3-diethylcyclohexane, and identify whether it is “cis” or
“trans”. (3pt) 19. Use the arrow-pushing convention to show the electron-movement mechanisms for the follow
two reactions. (5pt)
O+ CH3
O
CH3
a.
NH2
+ OH2b.NH2
OH2
T
T
T
1. Make sure you've really drawn "flflipped" chairs2. What's "ax" in one chair flflip is "eq" in the other.3. Process cis-trans4. Draw in H's on substituted carbons (easier to see ax/eq).
Torsional strain; any eclipsed conformation has torsional strain, repulsion beween bond-pair electrons.Steric strain: atom are unnecessarily close, and repel each other
Good mechanism must explain changs in:1. Bonds2. Formal Charges3. Lone pairs
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